1. Field of Invention
This invention generally relates to an exercise device. This invention more particularly relates to an exercise device that closely simulates a free-weight squat movement.
2. Background
Many of a person's daily events require the use of the lower body involving multiple muscle groups across multiple joints. For example, walking, running, climbing stairs, sitting or standing, bending down to pick up a child or an object etc. all involve multiple joint movements. Since these activities mainly involve the lower body and because they all involve multiple muscle groups across multiple joints, the optimal exercise for maintaining or increasing strength for daily activities of living should involve multiple muscles across multiple joints. In addition, most of these activities require balance to prevent tripping and falling. The exercise that most closely mimics or involves all of the same muscle groups and joints while increasing the stability of the body is the squat exercise.
The free-weight squat exercise is an important exercise because it is a triple-extension movement that requires use of multiple major muscle groups (e.g., the quadriceps, hamstrings and hip musculature) over three different joints (e.g., hip, knee and ankle) to operate in unison to complete the movement. The free-weight squat is performed while standing in an upright posture with weight resting over the upper back and shoulders. The ability to move the hips backward is what allows the exercise to incorporate the hip and hamstring muscles. This same movement is what also allows the smaller stabilization muscles of the abdomen, lower back, hip rotators, and calf to be used. Incorporation of so many muscle groups over multiple joints allows a person to increase strength of the entire lower body and is considered the optimal method to strengthen the lower body. The squat exercise also requires the body to use the smaller musculature of the abdomen and back to stabilize the body at the trunk as well as the calf musculature to stabilize the knee and the ankle joints. The use of the smaller stabilization muscles allows an increase in balance creating a more stable base. The squat exercise is safe and effective as long as it is performed correctly. A drawback to the performance of this exercise is that in order to perform it correctly a person needs to be instructed by a knowledgeable professional who can train them on the proper technique for the performance of the exercise and carefully watch them over multiple sessions to ensure the technique is continually performed correctly. The squat movement also allows for large amounts of weight to be lifted while performing the exercise. If a person were to perform the exercise incorrectly or fall, the weight could cause injury to the person. Since this exercise requires so many muscle groups across three separate joints, there is a wide margin within which a person could perform the technique incorrectly resulting in injury, if not properly instructed or supervised.
Many different types of leg exercise devices have been developed for use in the field of strength training, physical therapy and rehabilitation, and the like. More particularly, many different types of leg exercise devices that attempt to simulate a free-weight squat movement have been developed. These different types of leg exercise devices may be organized into two primary groups. The first group of devices utilizes an immovable upper back and shoulder support sled guided along two support rails. See U.S. Pat. No. 4,535,985 to Mask, U.S. Pat. No. 5,263,913 by Boren, and U.S. Pat. No. 5,941,803 by Chamberlain, et. al. Generally, in these devices, the user will push his/her feet against a foot plate thereby moving the user's upper back and shoulders on a sled along a fixed longitudinal axis defined by the device's support rails. In these devices, the only degrees of freedom allowed are flexion and extension of the user's hips, knees, and ankles. These devices do not allow the pelvis to translate freely out of plane as in a classic free-weight squat movement. Since the user's shoulders and pelvis cannot move independently, the squat motion performed does not recruit the user's back musculature to stabilize the user's upper torso. The second group of devices utilize curved path defined by a track frame. See U.S. Pat. No. 4,176,836 to Coyle and U.S. Pat. No. 5,411,458 to Giust. There are two major constraints inherent in the second group of devices. The first major constraint is that the user's pelvis, back, and shoulders, are all supported by the same rigid sled. The user's pelvis cannot move independently from the user's shoulders and thus the user's back musculature is not recruited to stabilize the user's upper body. The second major constraint is that the rigid sled is required to move along a predefined path defined by the track system. As a result, the user's upper body and leg joints are prevented from assuming the user's natural positions and form, which are inherent in a free-standing squat movement in which the user's upper body is free to move to whatever positions achieves a natural balance with respect to the user's feet. Another constraint of these devices is that they do not provide a means whereby a resistive force can be applied along the line of action perpendicular to the plane defined by the foot plate. In other words, these devices do not show how a resistive force can be applied along the same line of action with respect to that body as would be the case with gravity acting on a weighted barbell, as in a free-standing squat movement.
The present invention seeks to provide an apparatus that supplies additional advantages over the prior art and takes into account the aforementioned considerations.